Climate change poses a growing security threat and could cause conflict in the Arctic, a group of retired American generals and admirals said on Tuesday.

In a new report, the former military officers said the Pentagon had been caught out by the rapid changes under way in the Arctic because of the melting of the sea ice.

“Things are accelerating in the Arctic faster than we had looked at," said General Paul Kern, the chairman of the Centre for Naval Analysis Corporation's military advisory board, which produced the report. “The changes there appear to be much more radical than we envisaged.”

The prospect of an ice-free Arctic by mid-century had set off a scramble for shipping lanes by Russia and China especially, and for access to oil and other resources. “As the Arctic becomes less of an ice-contaminated area it represents a lot of opportunites for Russia,” he said. Oil companies were also moving into the Arctic.

"We think things are accelerating in the Arctic faster than we had looked at seven years ago," he said, saying the situation had the potential to "spark conflict there".

The CNA report deepens concern about the security risks posed by climate change. In March, the United Nations' IPCC, in a landmark report, also warned that growing competition for resources in a world under climate change could lead to conflict.

The report from the retired generals goes further, however, upgrading the climate risk from a “threat multipler” to a “conflict catalyst”.

In addition to the Arctic, the report warned climate change could lead to conflicts in developing countries.

“In Africa, Asia, and the Middle East, we are already seeing how the impacts of extreme weather, such as prolonged drought and flooding – and resulting food shortages, desertification, population dislocation and mass migration, and sea level rise – are posing security challenges to these regions’ governments. We see these trends growing and accelerating," the report said.

“Populations will likely become disenfranchised and even more vulnerable to extremists and revolutionary influences,” the report went on.

Other possible sources of conflict remain the intensifying competition for water, food and energy, the report said.